Going from 5 ohms speakers to 8 ohms

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Norm1968

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I am thinking of changing the speakers (5 ohms) on my Panny Rx-c300. Hoping to hear more bass. I connected the speakers from my Panny Rx-c100 (8 ohms) to the c300 and already the bass was more present. I've read that going from 5 ohms to 8 ohms speakers wouldn't affect the amplifier and that it would actualy make its life easier, can anyone confirm that? Would not want to burn the amp in the C300. There should be a ´´loudness'´ switch on the C300 as found on the C100. That would of created a deeper bass.
Thanks
 

jimmyjimmy19702010

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Hi Norm1968,

Switching to 8 ohm drivers will lower the RMS output of the amplifier. Whether this switch lowers the loudness of the blaster will be determined by the dB sensitivity of the original and replacement speakers.

The impedance (ohms) a speaker offers the amp doesn't determine how much bass it will produce. Apart from the physical properties of the speakers, cabinet tuning etc is what determines the audio output signature.
 

Norm1968

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Thanks Jimmy
Your right about the RMS lost going to 8 ohms.
So, although the C-300 speaker cabinets are made of wood, it doesn't mean that the sound will be better or that there will be more bass. If I want more bass, I would need to replace the speakers with some more dB sensitive speakers? The lower the dB sensitivity, the better?
I believe that the originals are pretty low quality compared to the ones used in the C100.
 

jimmyjimmy19702010

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The higher the dB the high the efficiency so the louder it will sound. The amount of bass is determined by cabinet tuning etc, not the RMS output of the amp. So in other words, it's possible to have a hugely powerful amp to have weak bass if the speakers it's powering have a limted low frequency range and output.
 

JVC Floyd

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Also a speaker designed with bass in mind goes a long way.
Speakers designed to play in the lower frequency range tend to have less distortion and handle more power , the trade off is you get a frequency gap between the highs and the lows.
 

Norm1968

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Thank you Jimmy/JVC for inlighting me on the subject.
Still need to learn some stuf before I get into speaker modifications.
Tonight I connected two Paradigm speakers and it sounds amazing. The bass... so nice. The C-300 amp is pretty good I suppose. The cabinets are the problem in my situation.
You are both right. Speaker design to reproduce great sound, do sound great.

Here is my setup at the moment

There it is. IMG_2771.JPG
 

hopey

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Look up ohms law. If you are increasing the resistance you wil loose volume. If you want more volume change to 4ohm speakers but these will draw more current. You can experiment with series and parallel circuits if using multiple speakers.
 

Superduper

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hopey said:
Look up ohms law. If you are increasing the resistance you wil loose volume. If you want more volume change to 4ohm speakers but these will draw more current. You can experiment with series and parallel circuits if using multiple speakers.
That's not nearly as simplistic as you make it. First, speakers are NOT rated in resistance, they are rated in impedance which is different. SPEAKERS ARE NEVER RATED IN OHMS RESISTANCE, except in the case of DC resistance, which is not a useful spec and virtually never coincides with the impedance rating. Resistance is static whereas impedance is dynamic. Secondly, each speaker driver is entirely unique in it's characteristics and your comments about going from 8ohms to 4ohms will result in more volume seems to suggest a rule that more volume can always be had with lower impedance speakers. This is only true if this change is made between drivers with nothing different except the impedance specfiications... same size, same cone material, same spl specs, same x-max rating, same manufacturer... etc. Yes, some manufacturer do manufacture the same basic driver with the only difference being the impedance but if the OP is replacing an existing driver from a boombox, there is no such animal. Bottom line, the statement that halving the impedance will result in higher volume is only true with the qualifier "with all else being equal" which is the problem since there is no such animal. There will always be differences whether great or small.

Now, from a practical aspect, sensitivity is far more useful specification for predicting loudness/volume. Why? Because doubling the power (or halving it) will only result in a 3 decibel difference in SPL (loudness) levels. It is not uncommon to find speaker drivers ranging from 82 to 100 decibels. A 85db 4-ohm driver will sound no louder than a 88db 8-ohm driver and this is at 1-watt power. A high efficiency 8 ohm driver is always preferable to a low efficiency 4 ohm driver because you can get the same or louder volume with less load, heat and wear/tear on the amplifier (with sensitivity difference of +3-db or greater).

Now, as to your last comment about "experimenting" with parallel and series speakers... why suggest such a thing to someone who might not understand the consequences and results of such actions? How about if he parallels 2 or 3 or 4 (4-ohm drivers)? And with 3.2-ohm drivers being common in boomboxes, how about if he parallels those? Who will pay for his amp if it goes up in smoke?
 

jimmyjimmy19702010

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Norm is spot on - the sensitivity of a speaker is key. BTW, you don't halve the amp output when you switch from 4 to 8 ohm speakers.

The larger the speaker, the easier it is to find high sensitivity speakers. My next DIY build will have 8 inch, 4 ohm drivers that have a 102dB sensitivity!! Those speakers will make a small, 12 volt 20 watts RMS per channel sound as powerful as a mains powered high amp!

So, in other words, max out the speaker sensitivity. I'd rather use high sensitivity 8 ohm drivers than medium to low sensitivity 4 ohm speakers to maximize loudness and aid an aging amplifier's chance of survival. :-)
 

hopey

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To keep on point with the thread. The amount of bass created by the speakers depends on the freuency response of the drivers. I would estimate the standard drivers would only go down to 50hz. You can easily increasethe bass response by finding replacemnet drivers that respond to lower frequencies such as 30hz. The most accessible are 4ohm car speakers.

Superduper said:
You forgot about voltage drop this is why the 8ohm speaker will have much less volume.
It makes no difference if you use 8 ohm or 80 ohm speakers, the available voltage to the speakers (load) remain the same. It is current that will drop and thus lower watts consumed. Forget about confusing the OP, I think you are confusing yourself.
Ohms law says the power out put is the same but the voltage drops and so does volume.
 

Superduper

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hopey said:
Ohms law says the power out put is the same but the voltage drops and so does volume.
OMG.

Ohms law says nothing of the sort, and it sure as heck says absolutely nothing about volume because ohms law has nothing to do with volume. Voltage, current, resistance are all variables in the ohms law equation and if you know 2 of the variables, then you can compute the third but your presumptions are flawed as you chose ohms and power as the 2 static variables, which is why your computation adjusts the voltage to compensate. Just because YOU chose static values for power output and ohms doesn't make it so. Ohms law is just a formula. Like any formula, you feed it garbage in, you get garbage out.

You clearly know just enough to get yourself in trouble. Please don't confuse the other members that maybe don't know and trying to learn something.

I assure you that changing the impedance of the load circuit in an audio amplifier will absolutely result in a change in the power output. If the output was the same, (i.e. 20watts), then volume is going to drop?
 

JVC Floyd

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The higher the impedance the lighter the load on the amp , the lower the impedance the greater the load . the impedance is the ohm rating of the speaker I.e the higher the number the less power draw , the lower the number the higher the power draw.
 

hopey

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There is no voltage regulation on Boombox's. They are designed for a specific load. What you are talking about only applies to mains power components.
 
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